The present invention relates to a chuck. More particularly this invention concerns a drill chuck.
A standard chuck has a body centered on and rotatable about a chuck axis and formed with an axially forwardly open tool recess. A plurality of angled guide passages open into the recess. Respective jaws are displaceable in the guide passages into and out of an advanced positions projecting into the seat. Mechanism on the chuck displaces the jaws into their advanced positions for gripping a smooth-shank bit in the recess. The jaws are angularly equispaced and moved radially synchronously, typically by engagement of teeth on the backs of the jaws with an internally threaded ring, so that the tool is gripped centered on the axis.
Nowadays it is increasingly common to provide drill bits of all sizes and uses with hexagonal-section shanks that are identical, so that they can be used in a standardized hexagonal-socket of a power tool. Such bit can in fact be solidly gripped by the standard three-jaw chuck, in which case they have little advantage over smooth-shank tools. Preferably, such a hex-shank tool is used in a standardized socket on a special-duty power unit, for instance in a screw gun or the like so that the tool can be quickly chucked and dechucked, without the necessity of tightening and loosening holding jaws.
Alternately an adapter can be fitted to an existing jaw-type chuck to allow quick chucking and dechucking of hex-shank tools. This system requires an extra part and adds considerably to the overall length of the power tool.
It is therefore an object of the present invention to provide an improved drill chuck.
Another object is the provision of such an improved drill chuck which overcomes the above-given disadvantages, that is which can be used with both hex- and smooth-shank tool bits.
A further object is to provide such an improved dual-duty drill chuck which is no larger in length or diameter than the known three-jaw chucks.
A drill chuck has according to the invention a chuck body centered on and rotatable about a chuck axis and formed with an axially forwardly open tool recess, a plurality of angled guide passages open into the recess, and a pocket open radially inward into the recess. Respective jaws are displaceable in the respective guide passages into and out of an advanced positions projecting into the seat and mechanism on the chuck can displace the jaws into their advanced positions for gripping a smooth-shank bit in the recess. A socket formed centered on the axis with an axially forwardly open polygonal-section seat is nonrotatable in the seat of the chuck body and axially displaceable in the chuck body into and out of a tool-releasing position. A latch is radially displaceable in the socket in the tool-releasing position of the socket between an inner retaining position projecting radially into the seat and an outer freeing position clear of the seat and projecting radially into the pocket. The latch is aligned radially with the pocket only in the tool-releasing position. The chuck body engages the latch and forces it into the inner retaining position except when the socket is in the tool-releasing position so that a polygonal-section shank of a tool formed with a radially outwardly open cutout can be fitted to the seat when the socket is in the tool-releasing position and is retained by engagement of the latch element in the cutout when the socket is not in the tool-releasing position. A lock member is radially displaceable in the chuck body between a locked position engaging the socket and preventing movement of the socket into the tool-releasing position and an unlocked position allowing movement of the socket into the releasing position.
Thus with this chuck a standard cylindrical- or smooth-shank bit can be chucked and dechucked in the standard manner by using the clamping jaws. A hex-shank bit is, instead, fitted to the seat of the socket which is them moved out of the tool-releasing position and locked to hold the bit in place. The chuck can have the same overall dimensions as a standard jaw-type chuck, but can serve perfectly for both types of bits. With the hex-shank bits it has the advantage of fast loading and unloading by simple actuation of the lock member.
According to the invention the latch is a ball and the socket is formed with a radially extending passage receiving the ball and open radially inward and outward. The passage is axially level with the pocket only in the tool-releasing position. The pocket can be formed as a radially inwardly open groove in an inner surface of the recess. The socket and chuck body are formed with axially interengaged polygonal formations inhibiting rotation of the socket in the chuck body. The formation of the socket is an axially rearwardly projecting polygonal-section extension. A spring braced between the socket and the chuck body urges the socket axially forward out of the tool-releasing position.
The chuck body in accordance with a feature of the invention is formed with a passage extending in a plane perpendicular to the axis and open radially inward into the recess and radially outward. The lock member is a pin displaceable along the passage and having an outer end projecting from the chuck body at least in the locked position. A spring braced between the chuck body and the pin urges the pin into the locked position. In one arrangement the socket has an axially forwardly projecting ridge and the pin has an axially rearwardly open groove aligned with the ridge only in the unlocked position of the pin. In this case the pin has a surface engageable with the socket and preventing same from moving into the tool-releasing position except in the unlocked position of the pin. The unlocked position is radially inward of the unlocked position. In another arrangement the socket is formed with a radially outwardly open groove and the pin is formed with a radially inwardly open cutout through which the socket extends with play only in the outer unlocked position. The cutout is offset at least partially from the groove in the locked position with the pin engaged in the groove so as to lock the socket against axial displacement into the tool-releasing position.
The guide passages in accordance with the invention are angularly spaced about the axis and open axially forward into the seat. The jaws have outer edges formed with teeth. The mechanism includes an internally threaded ring axially fixed but rotatable on the body and meshing with the teeth of the jaws. The mechanism also includes a sleeve surrounding the body and fixed to the ring. The lock member projects radially outward through the sleeve.